This invention relates to carbon-composite materials, particularly of the type used to form cathodes or cell linings of electrolysis reduction cells, especially those used for the production of aluminum metal, as well as parts of such cathodes and linings, and related products. More particularly, the invention relates to carbon composite materials that are erosion/oxidation-resistant and, desirably, that are wettable by molten aluminum.
The cathodes of cells used for the production of aluminum generally take the form of a lining made of carbon blocks, or the like, positioned along the bottom wall and sides of an electrolysis cell. A typical electrolysis cell 10 is shown in FIGS. 1 and 2 of the accompanying drawings. Where the surface 11 of the molten electrolyte 12 contacts the sidewalls 14 of the cell, the cathode 15 is often sloped as shown (this usually being referred to as the xe2x80x9cmonolithic slopexe2x80x9d of the cell lining) to reduce cell erosion caused by magneto-hydrodynamic (MHD) effects that may create excessive metal motion. Conductive anodes (not shown) dip into the molten electrolyte from above to complete the electrode combination required for electrolysis. The cathodic lining 16 is conductive and contacts the molten electrolyte 12 and also the pool 17 of molten metal as it is formed. Gaps 18 between the Spacers, in the form of short cylindrical stubs or buttons, are arranged in three groups spaced about the heat transfer basin and projecting into the heat transfer basin interior to maintain a prescribed space between the two basins. During use, that space contains a thermal transfer liquid, such as alcohol or glycol, serving as a thermal transfer medium between the two basins. A sterile drape, impervious to the thermal transfer medium, is disposed between the product basin exterior and the liquid thermal transfer medium to preserve the sterile nature of the product basin. Surgically sterile liquid, such as sodium chloride solution, is placed in the product basin and congeals on the side of that basin when the refrigeration unit is activated. A scraping tool is utilized to remove congealed sterile material from the product basin side to thereby form a slush of desired consistency within the product basin. Some users of the system employ the scraping tool to chip the solid pieces from the basin side.
As noted in the above-referenced Templeton patent (U.S. Pat. No. 4,934,152), the Keyes et al system has a number of disadvantages. In particular, the separate product basin must be removed and re-sterilized after each use. Additionally, the glycol or other thermal transfer medium is highly flammable or toxic and, in any event, complicates the procedure. The Templeton patent (U.S. Pat. No. 4,934,152) discloses a solution to these problems by constructing an entirely new apparatus whereby the product basin is eliminated in favor of a sterile drape impervious to the sterile surgical liquid, the drape being made to conform to the basin and directly receive the sterile liquid. Congealed liquid is scraped or chipped from the sides of the conformed drape receptacle to form the desired surgical slush.
The Faries, Jr. et al patent (U.S. Pat. No. 5,163,299) notes that scraping congealed liquid from the drape is undesirable in view of the potential for damage to the drape, resulting in a compromise of sterile conditions. As a solution to the problem, the Faries, Jr. et al patent (U.S. Pat. No. 5,163,299) proposes that the drape be lifted or otherwise manipulated by hand to break up the congealed liquid adhering to the drape. Although this hand manipulation is somewhat effective, it is not optimal, and often is inconvenient and constitutes an additional chore for operating room personnel. Accordingly, several of the Faries, Jr. et al patents (e.g., U.S. Pat. Nos. 5,331,820; 5,400,616; 5,457,962; 5,502,980; 5,653,938; 5,809,788; 5,857,467; 5,950,438; 6,003,328; and 6,035,855) resolve the problem of manual drape manipulation by disclosing various techniques and/or dislodgment mechanisms to automatically remove the congealed liquid adhering to the drape without endangering the integrity of the drape.
The Templeton patent (U.S. Pat. No. 4,934,152) further discloses an electrical heater disposed at the bottom of the basin to convert the sterile slush to warmed liquid, or to heat additional sterile liquid added to the basin. Templeton describes the need for such warm sterile liquid as occurring after a surgical procedure is completed to facilitate raising the body cavity of the surgery patient back to its normal temperature by contact with the warmed liquid. However, there are a number of instances during a surgical procedure when it is desirable to have simultaneous access to both warmed sterile liquid and sterile surgical slush. Accordingly, several of the Faries, Jr. et al patents (e.g., U.S. Pat. Nos. 5,333,326; 5,429,801; 5,522,095; 5,524,643; 5,615,423; 5,653,938; 5,816,252; 5,862,672; 5,857,467; and 5,879,621) disclose a manner in which to simultaneously provide both surgical slush and warmed surgical liquid during a surgical procedure by utilizing a machine having plural basins with each basin either producing surgical slush or heating a sterile liquid. This machine typically utilizes a single surgical drape that forms a drape receptacle within each basin to collect sterile slush and heated sterile liquid produced by the machine in the respective basins.
In addition, several of the drapes and thermal treatment systems disclosed in the above-mentioned patents and copending applications include specialized features to enhance various aspects of thermal treatment system operation. For example, some of the specialized features may include: bladder drapes (e.g., as disclosed in U.S. Pat. Nos. 5,809,788; 5,950,438; and 6,003,328); drapes having plates or disks (e.g., as disclosed in U.S. Pat. Nos. 5,457,962 and 5,502,980); leak detection drapes (e.g., as disclosed in U.S. Pat. Nos. 5,524,643 and 5,816,252); reinforced drapes (e.g., as disclosed in U.S. Pat. No. 5,857,467); drape indicators and corresponding thermal treatment system detection devices to ensure sterility by enabling system operation in response to detecting a sterile drape placed on the system (e.g., as disclosed in U.S. Pat. Nos. 5,653,938 and 5,879,621); drapes having indicia to direct placement of the drapes on thermal treatment systems (e.g., as disclosed in U.S. Pat. No. 5,615,423); surgical drapes constructed of materials having a coefficient of friction in a particular range and/or drapes including attachment mechanisms such that a drape may withstand being drawn under a dislodgment mechanism (e.g., as disclosed in U.S. Pat. No. 6,035,855); and a stand to elevate objects within a heated basin above the basin floor (e.g., as disclosed in U.S. patent application Ser. No. 08/807,095) and/or a heater configured to cover a portion of the basin (e.g., as disclosed in U.S. patent application Ser. No. 09/046,090) to prevent the drape from overheating and puncturing when objects are placed within the basin.
The above-described apparatus may stand some improvement. In particular, thermal treatment systems or machines are generally utilized for certain aspects of a medical procedure. These machines are typically operated prior to or during the medical procedure to enable a sterile medium to attain a desired temperature and/or form suitable for that procedure. The machines are positioned within an operating room or other facility proximate the medical procedure site and patient. Since the machine treats sterile media in a sterile field, sterile personnel (e.g., personnel that have taken the necessary precautions enabling them to interact with objects in the sterile field without contaminating that field) are required to operate the machine to prevent contamination of the sterile field and injury to the patient. Thus, the machine either provides sterile personnel with an additional task of controlling and monitoring the machine, or requires additional sterile personnel to perform the task, thereby increasing procedure costs and crowding the procedure site.
When the thermal treatment system is positioned within the facility beyond the proximity of the operator, personnel must physically attend to the machine to manually operate the controls. With respect to slush machines having dislodgement mechanisms, personnel may be required to repeatedly attend to the machine to operate the machine and monitor collected slush during the procedure. Further, the machine temperature indicator is generally poorly visible, and may similarly require personnel to be in close proximity to the machine to ascertain settings and liquid temperature. The process of personnel frequently attending to the thermal treatment machine may become distracting to the procedure, especially when numerous machine inspections and/or control adjustments may be required. Moreover, frequent inspections and/or adjustments may divert personnel from their medical procedure tasks at inopportune times, such as when complications arise, thereby increasing risk of injury to the patient.
In addition, operating room personnel are generally engaged in various activities during medical procedures. These activities typically include tasks ranging from monitoring and operating medical equipment to handling medical instruments. Since the personnel frequently employ their hands to perform the tasks, operation of the thermal treatment machine typically requires a current task to be completed or interrupted in order to enable personnel to utilize their hands to operate the machine controls. As a consequence, interrupted tasks may be omitted due to personnel oversight, or repeated entirely since the precise interruption point may not be recalled. This generally tends to decrease efficiency and may prevent crucial tasks from being completed at the proper time during the medical procedure, thereby risking injury to a patient.
Accordingly, it is an object of the present invention to remotely control operation of a thermal treatment system to thermally treat a sterile medium.
It is another object of the present invention to enable non-sterile personnel to remotely control operation of a thermal treatment system to thermally treat a sterile medium during a medical procedure.
Yet another object of the present invention is to display information pertaining to treatment of a sterile medium by a thermal treatment system in a manner visible to users located at extended ranges (e.g., distances extending to ten or more feet) from the system.
Still another object of the present invention is to remotely adjust various operating parameter settings of a thermal treatment system to control thermal treatment of a sterile medium to a desired temperature and/or form (e.g., slush).
A further object of the present invention is to remotely control a thermal treatment system dislodgment mechanism to collect a desired quantity of surgical slush.
Yet another object of the present invention is to control operation of a thermal treatment system to thermally treat a sterile medium via a foot actuated switch or control unit.
The aforesaid objects are achieved individually and/or in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto.
According to the present invention, a thermal treatment system for thermally treating a sterile medium or liquid is controlled via a foot actuated switch or control unit to thermally treat the sterile medium to a desired temperature and/or form (e.g., slush). The thermal treatment system includes a basin recessed in a system top surface, while a surgical sterile drape is placed over the system and within the basin to form a drape container for containing the sterile medium. The basin may be configured to cool the sterile medium and form sterile surgical slush, or heat the sterile medium to provide warm sterile liquid. A dislodgment mechanism may be employed within a cooling basin to manipulate the drape and dislodge frozen pieces of sterile medium adhered to the drape. Information pertaining to the sterile medium and system operation may be displayed on a system display that has dimensions sufficient to provide visibility of the information to users located within extended ranges (e.g., distances extending to ten or more feet) from the system. The foot actuated switch or control unit is in communication with the system to control system operation. The foot switch typically includes pressure sensitive transducers to facilitate entry of commands and operational parameters for transmission to the system in response to actuation of those transducers by a user.
Alternatively, the thermal treatment system may be responsive to a remote control unit to enable users to control operation of the system remotely. The remote control unit may control various operating parameters and features of the system (e.g., desired temperatures, power, display, dislodgment mechanism, etc.), and preferably emits system commands in the form of code signals. A receiver is employed by the thermal treatment system to receive the transmitted signals and facilitate system operation in response to those signals.
In addition, the foot actuated switch and remote control unit may be utilized with thermal treatment systems having a plurality of heating and/or cooling basins with each basin being individually controlled. Moreover, the systems disclosed within the above-mentioned patents and copending applications may similarly be configured to be responsive to the foot actuated switch and/or remote control unit in substantially the same manner described above.